1. Field of the Invention
The present invention relates to a method and an apparatus for slowing the discharge process of a battery, preferably a battery of a hand tool machine, with the load shut off, in which the battery is equipped with a monitoring circuit evaluating and detecting its operating variables related to the energy supply in or the charge state of the battery.
2. Description of the Related Art
For example, DE 41 06 725 A1 describes an apparatus including a battery equipped with a monitoring circuit, which detects and evaluates the operating variables of the battery. These operating variables include, for example, the temperature of the battery, the charging and discharging currents of the battery under load. This circuit also detects the resting current and the spontaneous discharge of the battery and limits the discharging of the battery at a predetermined limiting voltage, in order to avoid a total discharge that would shorten the life of the battery. The operating variables detected by the circuit can finally be used for control of operation of a load connected to the battery or for control of the charging process at a charge station.
Generally discharging of a battery cannot be avoided, even if it is not under a load due to operation of consumers with it. This discharging process is even accelerated because the evaluation circuit described in DE 41 06 725 A1 continuously draws energy from the battery. Thus it is desirable to slow the discharging of a battery as much as possible so that the battery remains useful for the longest possible time for operation of a load, for example of a hand tool machine. Examples of hand tool machines having such batteries are drills, screwdrivers, hammer drills, grinders, saws, etc.